Rheostat.



YPATENTBD APR. 28, 1908. J. w. MERTZ.

RHEOSTAIT. APPLIOATION I'ILBD JAN. 14, 1908.

3 SHEETS-SHEET 2.

W/TNESSES ATTOHNE YS PATENT AER. 28, 1908.

SlNGLE-MUL BUS BUS

W/ TNE SSE S Mam m A TTOHN E Y8 UNITED STATES PATENT UFIBICE.

RHEOSTA'I.

Specification of Letters Patent.

Patented. April 26, 1908.

Application filed January 14, 1908. Serial No. 410,721.

To all whom "it may concern:

Be itknow u that l, Jenn WiLLiAn Micu'rz, e citizen. of the United States, and a resident of h'lount (lltlllCIlS, in the county of V Mecoinh and State of lrlichigen, have. in-

vented at new and improved .ltheostztt, of which the following is it full, clear, and exuct description.

My invention relates to rhooststs suitable for general use, and more particularly to a type of rhoostot-ol special service in connection with are lamps for the production of moving pictures.

The IIIOBOPtLltlGUltl purpose of my in Von tion is to give the. operator a, more extensive control over the current so that he can closely grznluute the resistance and govern it completely within wide limits.

My invention further relotcs to certain. details in construction whereby the general eliicioncy of the rheostut is increi-isml.

Reference is to be had to the acconn'ia'ny ing drawings forming a port of this specilication, in which siniihn' characters of rcler onco indicotc corrospoiuling ports in all the figures.

Figurev l is :L .l'ragnicntary front view ol" the rheostet conipleto the lower portion of the figure showing the coils and the upper portio n showing the switch handles provided with hand switches for inanipuluting the re sistzince; Fig. 2 is a. fragmentary rear view of the rhcostziuthis view showing particularly the hack of the. switch handles and the manner o'l connecting the coils to the handy switches; Fig. 3 is a. VOItlC-tl-l section upon the line 3-"3 of Fig. 2, looking in .t is direc tion ol the arrow end showing how the coils and the switch hondles are supported upon the Tl'ttll'lQWOlli, and Fig. i is a diagram of the switches, the windings and electrical connections.

Two flat hers 5, (5 constitute respectively the top and bottom pieces oi" the framework, and are connected together by tubular posts 7, 8 secured in position by bolts 7, 7. By loosening these bolts tho lhtt lHUS may be disconnected from the tubular posts so as to disassemble the ports. Feet 5) are bolted to the bottom her (i and serve to support the latter out oi engagement with the lloor or other surface upon which the rheostat rests. A panel board is shown at 10 and secured upon supporting rods 11 bent suhstoi'itielly into L shape (see Fig. 3) and provided with 1 portions .2 whichv are secured to the upper her 5 by aid bolts 13. The panel hoard thus projects outwardly a. little from the her 5.3 and. is tl'ierel'iy rendered more convenient and accessible to the operator.

Mounted upon the panel heard 10 are binding posts 14, 15 which are connected with conductors to, 17 through which the current flows in and out of the rheoste-t. A metallic strip connects the binding post 14: with a pivot post 20, the latter being pro-' vidcd with binding post 19 (see 2) upon the hack of the panel for this purpose. Upon the pivot post 20 is mounted :1 switch knife 21 free. to swing upon the pivot post as a center. A contact fork is mounted above the pivot post 20 and a, contact tori: 23 is disposed below this post and adopted to he engaged by the switch knife 21. A. lnn'idle 24 is mounted upon the switch knife for turning it upon the pivot post 20.

A number of other pivot posts 25, 26, I27, .28 and 29 are. disposed in it row, and mounted respectively upon them mid free to swing are switch knives 3t), 31, 32, 33 and 34'. Disposed. }..u'trtially within the paths of these switch knives are contact forks 35, 36, 37, 38, 39, and mounted upon the switch knives l r the purpose of imniipulating them handles 40, ll, 42, 43, 44, which, like the handle 24. are of insulating material.

The pivot post 29 is provided with a. binding post 29 (see Fig. 2) upon the rear locc of the switch panel and this binding post is connected by an insulated wire 45 with a. similar binding post 28, the latter being connected with the pivot iost 28. The contact forks I57, 38 are similarly provided with binding posts 37, 238 (see Fig. 2), these bii'iding posts being connected. together by a. metallic strip 46. The pivot posts 26, 27 are provided with binding posts 26, 27, connected together by a metallic strip 47. post, is provided with a. ljiinding post 25 which is connected by an insulated wire 48 with the bindii'igpost 15. The contact forks 23 and are provided with binding posts 23, 35, which ore connected together by an insulated wire 49.

I use two groups 50, 51 of resistance wind ings, each group consisting ol' any convenient number. In the particular instance here described, there are six wirulings in each group. The group is located upon the front 01' the machine, that is, nearest the The pivot winding 59 with the contact fork 39.

switches are open.

0 portions of thc currents 5 rhcostat as a whole.

switch panel 10, and its windings are designated 58, 59, 60, 61, 62, 63. The windings of the rear group are designated as 52, 53, 54, 55,56,57.

For the purpose of supporting the various windings each is connected with a metallic clip 64 having spring arms 65 of a general U shape and adapted to grip a spool 66 of nsulating material, The spools 66 are arranged in pairs and held in position by bolts 67 which ass directly through the flat bar 5. Similarl clips 68 engage spools 69 which are arranged in pairs and supported upon bolts 70 (see Fig. 3). The arms 66 are malleable and are bent around the spools or clenched thereupon, so as to hold the windings.

The windings 52, 53, 54, 55, 56, 57, constituting the group 51, are connected together in series by short piecesof wire 71, 72. An

20 insulated wire 73 leads from the binding post :23 of the contact fork 23 Another insulated wire 74 connects together the two groups 50, 51 and in doing this, connects in series the two adjacent windings 57, 58. A wire 75 connects the winding 58 and wire 74 with the contact fork 22 which is provided fo "his purpose with a binding post 22 (seiflg. 2). A wire 76 connects the winding 62:- 1 ",n the binding post 15. A wire 77 leads from the lower end of the coil 62 to the contact fork 2-16. The windings of the group 50 are connected togetl'ier by short wires 78, 79, 86, 81 and 82, as will be understood from the lower left-hand portion of Fig. 4. A

to the Winding 52.

35 wire 83 connects the pivot post 26 with the upper end of the winding 61. A wire 84 establ shes communication between the lower end of the winding 60 and the contact fork 38. A wire 85 connects the lower end of ltpe 1e upper end of the winding 59 is connected by a wire 86 with the pivot post 28.

For convenience some of the wires, such as 82, 85, 86, are led downwardly through the 45 tubular posts 7, 8, being thereby hidden and also protected.

The switch panel 10 is made preferably of slate, but I do not limit myself to the use of this material, nor, indeed, to the use of any 50 particular material for any part of the device.

The resistance windings are made preferably of steel.

The operation of my device is as follows: I will suppose that at the start all of the The connection may be traced diagra mmatically in Fig. 4. For convenience in tracing the various circuits, I will omit specific rcfcrcnw to the various bind ing posts, clips and the like, constituting path, and will refer chiefly to the windings and wires constituting the essential parts of the circuits. By manipulating the switchcsl am enabled to give a great range to the resistance oli'crcd by'thc Suppose, first, that l 1 desire the rheostat to afford a maximum of resistance. I simply lower the handle 24 so that it engages the contact fork 23. The other switches remaining open, the circuit may now be traced as follows: conductor 16, strip 18, pivot post 20, switch knife 21, contact fork 23, wire 73, windings 52, 53, 54, 55, 56, 57, in series through their connecting wires 71, 72, next through wire 74, winding 58, wire 82, winding 59, wire 81, winding 69, wire 80, winding 61, wire 79, winding 62, wire 78, Winding 63, wire 76, binding post 15 to wire 17.

It will be noted that all twelve of the windings are thus thrown in,- and consequently the resistance is at a maximum. Hence, the current is out down to a minimum, and if used in lighting, the light is weak.

Suppose, now, that the operator wishes to suddenly increase the light to a slight extent. He simply raises the handle 41, thus causing the switch knife 31 to engage the contact fork 36. The circuit above traced in series throughout all of the windings is not broken, but the contact of the switch knife 31 with the contact fork 36 diminishes the total resistance of the circuit. This is because when the current gets to winding 61 it need not all pass through the wire 79, but a portion can, follow a shorter path, to wit, wire 83, pivot post 26, switch knife 31, contact fork 36, wires 77, 78, 63, 76, post 15 and conductor 17. The net result is that the current has, durin a part of its course, a double ath, and this, under Ohms law, necessari y lowers the total resistance, though, as it affects a comparativcly small part of the circuit, the lowering in resistance is comparatively slight. To state the same thing another way, the current splits and part passes in series through all of the windings, the other part skippin winding 62. Similarly, if the switch handles, 42, 43 and 44 he raised so that the switch knives 32, 33, 34 engage the contact forks 37, 38, 39, the windings 61, 60, 59, are affected. like the winding 62, the total resistance being thus lessened. For instance, if the switch handle 44 be raised, we have the same circuit as before, to wit, one traversin all of the windings in series, but from this circuit we have a shunt. circuit which skips the winding 59. With all of the switch handles 4.1, 42, 43, 44 ralised, the resistance of the grou 51) is very low, being not much more than lialf the resistance of this grou when the switch handles 41, 42, 43, 44 are ail down. Since, however, the windings of the group 51 are always in circuit and are always in scrics with cach other, with icfcrence to thc current through thcm, the total resistance causcd by a movement of any one of the switch handlcs4l, 42, 43, 44 is not very great. Suppose, now, that we raise the switch handle 24 so that the switch knife 21 engages the contact iork 22.

The current new passes through the grou p 50 only, the circuit being The current thus passes in series throu h the grou alone. If, now, the current passing t irough this group is too weak (as indicated for instance, by weakness in the lights), the switch handles 41, 2, 43 and 44 are raised in succession, thus allowing more current to pass. If the lights are still too dim, I raise the switch handle 2-1. This doubles the amount of current. which would pass if the switch handle 24 alone w re raised.

(iare must be exercised not to have/the switch handle 24 lowered at the time when the switch handle 40 is raised, for the reason that this would form a short circuit. It may sometimes happen, however; that a short circuit is needed, and inthis event the two switches n'ientioned may be given the relation thus stated.

It will be noted that the switch handles 41, 42, 43, 44. may be operated independently for the purpose of reducing'the total resistance of the group 50. Ii only one of these switch handles be raised, the total resistance is'not atl'ected very much, but all four, or any less number otthcm, may be raised at will, the resistance may be varied considerably, this effect being entirely independent of whether the two groups are connected in series or in parallel.

As the switches represented by handles 41 42, 43, 44 are used i or the purpose of breaking up the series connections, I find that workn'i'en and electricians designate these switchesas Series Busters, I therefore designate them by the legend Bus as indicated in Figs. '1 and 4. The switch represented by the handle 40 being used mainly for thepurpose oi connecting the groups 50, 51 of windings in multi do with each other, I designate as the multiple switch and in practice usually mark it with the legend Mul windings, some of said electrical connections extending through said tubular posts.

2. In a rheostat, the combination of a pair of bars provided with openings, tubular posts extending through said openings, fastening members for securing said tubular posts within said openings so that the parts may be readily disassembled, and windings supported upon said bars.

3. In a rheostat, the combination of a winding, clips connected. with said windin and provided with U shaped portions of malleable metal, insulating members engaged by said U-shaped members, said U- shaped members being bent so as to hold on i to said insulating members, and connections for said windings.

4. In a rheostat, the combination of a framework, windings supported upon said framework and provided with electrical connections, a switch panel, and rods connected with said switch panel. and bent into L shape, said rods bein connected with said framework, and a pIurality of switches mounted upon said switch panel and connected with said windings.

5.,In arheostat, the combination of a framework, a pluralit of resistance windings supported u on saii, framework, a switch panel, switc res mounted upon said switch.

panel, and connections from said switches to "said windings, the arrangement of said con nections being such that by moving said switches said windings may be connected either in series or in parallel as desired.

6. In a rheostat, the combination of a framework a rou of windin smounted.

upon one side thereof and connected in series with each other, a grou of windings mounted upon the other side t iereof and connected also in series with each other, and means controllable at will for connecting the windings of said last-mentioned group so as to form an additional short circuit from one of said lastmentioned windings to another, thereby diminishing the total resistance of all of the windings.

7. In a rheostat, the combination of a plurality of windings connected in series, and means including; a plurality of hand switches for short circuiting said windings so as to divide the current flowing through them; a portion of said current passing in series through all of the windings and a portion of said current'bcing shunted oil so as to skip a portion of said windings, I

Inutestunony whereof I have signed my name to this specification in the presence of two subscribing witnesses. 4

JOHN WILLIAM MERTZ.

Witnesses W. J. JACK, PAUL VAN Aonan. 

